I have the Shadow Master up to lvl 18 already so I have decided to go with BoI and will have that maxed by lvl 89( I am at lvl 78 now). I figured that by the 1 point put in venom and plus skills that a lvl 11 venom at least gives a little poison to prevent monsters from healing. I kind of like fully synergizing the skill. It makes it feel like a pure pheonix build without the traps and just a point into each of the shadow skills(Except ShadowMaster).